Control of belt tension in paper machines



April 27 {1926. U 1,582,322

.F. w. WARREN CONTROL OF BELT TENSION IN PAPER MACHINES Filed April so. 1925 2 Sheets-Sheet 1 fl ATTORNEYS April 27 1926;

w. WARREN CONTROL OF BELT TENSION IN PAPER MACHINES Filed April 30. 1925 2 Sheets-Sheet 2 INVENTOR 7% ATTORNEY Patented Apr. 27, I926.

NT OFFICE.

FRANCIS W. WARREN, OF PARIS,

CONTROL-OF BELT TENSION IN PAPER .MACHINES.

Application fileduflpril so, 1925.- Serial No. 26,867.

To all whom it may concern:

Be it known that I, FRANCIS IV. IVARREN, a citizen of the-United States, residing at Paris, France, have invented certain new 5 and useful Improvements in the Control'pf Belt Tension in Paper Machines; and I don hereby declare the following to be a 'full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

l of great importance to produce and maintain an appropr ate tension 1n the paperforming wire, the carrying felts and the 20 paper web and it is the object of the present invention, more particularly, to control in. an improved manner the tension in these felts, webs of paper, and-especially in the paper-forming wire.

In the F ourdrinier or wet end of a papermaking machine an endless belt in the form of a wire fabric is caused to travel by frictional contact with power-driven rolls over a series of table rolls. After passing over the table rolls the wire proceeds over a series of suction boxes and then around oneof the power-driven rolls termed a. couch roll,

the meshes of the wire and, in order to facilitate this action and more especially, to cause thepaper fibres to properly arrange themselves in felted relation, the paper-forming wire is given a lateral rocking or shaking motion from the breast roll'to the first suction box. T

The wire over the suction boxes is prevented from shaking by the suction, and although the mechanism for imparting the rockingor shaking motion to the table rolls is usually designed so as to effect a relatively large, movement of the table rolls which are near the breast roll, and a relatively small movement of those table rolls which are-near the suction "boxes, nevertheless because of the relatively reat width of the wire screen, there is pro need a variation inthe tension of the wire throughout its width adjacent the first suction box. Wires of from 156" to 200" in width are not \uncommon and there is not only produced a variation in the tension but not infrequently a movement of the strands of the wire fabric relative to'one another. Alt

though this movement is of relatively small magnitude it produces rapid wear of the wire.

It is usual to provide a roll, termed a stretch roll, in such position as to bear upon the upper surface of the vwire as it returns "from the couch roll to the breast roll for the purpose of, producing a proper tension in the wire to cause it to operate in the desired manner. This stretch roll is journaled in vertically adjustable bearings,

but, in accordance with the usual practice, these bearings are rigidly fixed to their supwire at each stroke of the shake. It has also hitherto been proposed to independently journal the opposite ends ofthe stretch roll and this would have to a certain extent -f alleviated the stretching of the wire had it not been for the fact that the journaling mechanism employed was so constructed that I 1ts moving parts were of a relatively large mass and therefore possessed relatively great inertia. In these prior machines, therefore, the shake motion continued to cause stretching of the wire and neither the cause of the stretching nor its remedy was discovered.

It will be understood that the stretching of the Fourdrinier wire above referred to it highly objectionable for the reason that it reduces the life of the wire which is extremely expensive to replace. The stretching of the edges of the wire causes it to wrinkle and therefore lie unevenly on the table rolls and when it passes between the couch rolls and the. breast roll, these wrinkles are compressed. Then as the wire proceeds, they are partially straightened out and eventually causing it to crack.

This tendency of the edges of the wire to stretch because of the action of the shake motion has been largely Overcome by the present invention and according to this invention the wire is operated under a condition of tensional equilibrium produced by a stretch roll which with its moving parts possesses a minimum of inertia, this roll being arranged to float, or in other words, to be freely mov-' able vertically at each end under the support of the wire. The vertical movement of both ends of the roll is resiliently op. posed both upwardly and downwardly. When the shaking motion tends to pull one side of the wire more than the other, the floating roll is slightly lifted by the wire and the stretching reduced. The resilient mounting of the ends of the roll causes a variation in the initial tension produced by the weight of the roll in accordance with the lifting or sagging of either side of the wire.

The improved 'apparatus of my invention includes a journal bearing disposed at each side of the Fourdrinier wire andcarrying the journals of the stretch roll which extends throughout the width of the wire, and

vertical guides for each of these journal bearings which allow the roll to move freely either up or down under the support of the wire. Means are also included, such for example, as a pair of spiral springs, one arranged above and the other below each journal bearing for increasingly opposing the movement of the roll either above or below this floating position. In addition, an indicating device is provided so that the total tension on the wire may be read at any instant, and means for independently adjusting the vertical position of the springs for the purpose of equalizing the tension throughout the width of the belt.

The invention will be better understood by referring to the accompanying drawings which illustrate by way of example a. specific embodiment of the invention. In these draw1ngs Fig. 1 1s a view in elevation of the Fourdrinier part or wet end, of a paper making machine embodying-my invention.

. Figs. 2 to 5 inclusive are detailed views illustrating the construction of the bearings at each end of the tension or stretch roll.

Fig. 2 :is an end elevation of the journal bearing. vertical guides and their supportf Fig. 3 is a vertical section taken on line 33 of Fig. 2.

- Fig. 4 is a horizontal section taken on line 4-4 of Fig. 2.

Flg. 5 is a vertical section taken on line 5 -5 of Fig. 4.

Fig. 6 is a view similar to Fig. 2 illustrating a modified form of the journal bearing,-

vertical guide means, and adjustable spring support, and

Fig. 7 is a transverse section taken on line 77 of Fig. 6 looking in the direction of the arrows.

Referring now to these drawings, the Fourdrinier-wire 10 forms'an endless belt which passes from the breast roll 11 over the table rolls 12 and the suction boxes 13 to the guide rolls-14 and the couch rolls 1 5 and 16. The wire passes around lower couch roll 16 over supporting roll 17, underneath the tension or stretch roll 18 and over a second supporting roll 19 back to the breast roll 11.

The paper-forming wire 10 is driven continuously in a. direction to carry the upper part of the wire over the table rolls 12 from breast roll 11 toward the suction boxes 13, power being applied to the shaft of lower couch roll 16. For this purpose a suitable clutch (not shown) is provided on the shaft of roll 16 for starting and stopping the wire. The paper stock or pulp supplied by means of a trough 20 to the head box 21 flows over apron 22 and underneath the sluice 23 onto the moving wire. It will be understood that the wire 10 is s ightly wider than the web of paper whichit is desired to form and according to present practice, wires having a width of from 156 to200" are not unusual. Along each edge of the portion of the wire passing over the table rolls, and driven by frictional engagement therewith, there is a deckle strap 24;. These deckle straps serve to keep the liquid pulp upon the wire and prevent it from overflowing the edges of the wire as it emerges from the sluice 23 and spreads out in the form of a thin layer. The deckle straps are of endless construction and are supported on rolls 25, 26, 27 and 28.

As the wire 10 passes over the tab'e rolls, it is necessary that it be kept flat and smooth and for this purpose, suitable tension is applied to the wire by means of the tension roll 18 which isconstructed in accordance with the principles of my invention and which will be described in detail below. As mentioned previously, the portion of the machine between the breast roll 11 and the suction boxes 13 is rocked or shaken by suitable mechanism. This. mechanism is not ll. lustrated, but it wiltbe understood that it causes a movement or shaking of the table rolls and wire 10 thereon in a direction transverse to the direction of movement of the wire. This motion causes the fibres of the paper'pulp to intermingle and interlock with one another as to produce, when the moisture has been removed and the paper web dried, a tough and strong product.

Tension or stretch roll 29 is slightly greater in length than the width of wire 10 and is supported at each end by an improved take-up hearing which is indicated generally by reference numeral 30 and one of which is located on each side of the machine. The

take-up bearing on the side ofthe machine nearest the reader is shown in Fig. 1 and a similar bearing is employed on the opposite side of the machine.

In this take-up or tension roll bearing the journal 31 is carried in a journal bearing 32 which is composed of similar upper and lower sections appropriately bolted together by bolts 33 as may be seen in Figs. 4 and 5. The journal bearing32 is thus a unitary structure in which journal 31 is freely rotatable. Jonrnahbearing 32 is mounted so as to be freely slidable in the vertical direction in a frame-work 34 COll'lPOSC'd of sections secured ogether by bolts 35 and cast hollow so as 0 form a housing for the jour nal bearing Each of these frame sections has a pair of relatively narrowvertical faces 36 and 37 respectively which co-act with flat faces on journal bearing 32 and serve as vertical guides therefor. The fiat faces of bearing 32 which co-act with these guides are of considerable length, the exterior of the. sections of which bearing 32 is constructed being of rectangular shape, so that the bearing slides freely in the guides 36 and 37 without any tendency to bind or stic \Vithin the chamber of the frame-work in which bearing 32 slides, there is provided a pair of spiral springs 38 and 39 respectively above and below the bearing. 3 These springs are of similarstrength and cooperate with frame 34 and bearing 32 to hold the bearing normally in position midway between the top and bottom of the guide-ways. They are held in position by projections 40 and 41 on frame 34 and 42 and 43 on respectively the upper and lower sections of bearing 32. Each pair of cooperating projections have interfitted cone shape seats as indicated in the drawings to assist in maintaining the alinement of the bearings when either of the,

springs is fully compressed. Tl1e.framework 34 is equlpped with a clamp support 44 loosely encircling a threaded post 45 so that it is free to move up and down over the threads thereon. Hand wheels 46 and 47 engage the threads of shaft 45 and serve to adj ustably hold the support 34 between them and thus afford a ready means of raising or lowering the tension roll bearing 30 as a whole.

As will -be understood from Fig. '1, the.

by a. cross member 58 which is removably tension or stretch roll 29 is supported upon the Fourdrinier wire screen 10 and the weight of this roll is suchas to cause a-total tension of about 200 pounds in the wire, this being the usual tension in a relatively wide wire. A pair of semi-circular strips 48 and 49 carry pointers 50 and 51 respectivelyand are fastened upon the outer end of journal. bearing 32 in proper positionto cooperate with scales onthe frame 34. .By adjusting" hand wheels 46 and 47 the tension roll bearing 30, both at the front and also at the rear of the machine, that is, at each side of the wire 10, may be vertically adjusted so that the pointers 50 and 51 indicate zero on the scales. In this position neither of springs 38 and 39 of either bearing 30 is stressed and the tension in the wire 10 is caused entirely by the weight of roll 29.

If the weight of tension roll 29 is not uniform from end to end, this can be compensated for by adjusting the tension roll bearing 30 at one side of the wire or the other so as to compress spring 38 or spring 39 and thereby increase or decrease the tension on the wire at that side of the machine. Springs 38 and 39 may not be of the same size as indicated but may be of difi'erentstrengths in orderto provide, in combination with the weight of the roll, the proper tension on the wire 10. Different strength springs may also be used at the opposite ends of the roll 29 to secure proper compensation for longitudinal variation in the weight of the roll. Also, if it is desirable to operate the paper-forming wire 10 at a higher or a .lower total tension than 200 pounds, both of the stretch roll bearings 30 can be raised or lowered by manipulating hand wheels 46 and 47 and reading. the tension on the scales provided. The total tension of the wire may be read on the scale at the extreme left as viewed in Fig. 2 and the tension per inch of width of wire may be read on the opposite scale at the extreme right. The other two scales, however, indicate the pressure exerted by the springs in pounds.

The modified form of tension or stretch roll bearing illustrated in Figs. 6 and 7 is operated in a manner similar to the bearing above described, and possesses certain additional features of advantage. In this modification a rigid rod or post 52 is secured to the upper section of journal bearing 32 and asimilar rod 53 is secured to the lower seced upon these two rods respectively, the inner ends of the springs pressing against the journal bearing sections, and the outer ends of the springs being confined by the spring support 54;

The spring support 54 is a frame structure of rectangular, form having two upright members 55 and 56 which are joined at thebottom by a cross member 57 and at the top P0 fastened to the upper ends of the uprights 55 and 56 by means of bolts 59. The outer ends of springs 38 and. 39 consequently bear against. the members 58 and 57 respectively. The rods 52' and 53 which are coaxially ar- 135 ranged pass through apertures in the cross members 58 and 57 respectively, these apertures serving as guide-ways in which the rods loosely fit and freely slide. The members 58 and 57 are provided with bosses so as to increase the bearing surface in contact with the rods 52 and 53.

The flat sides 60 and 61 of the journal bearing 32 are preferably spaced from the interior faces of the uprights 55 and 56 by an amount which will allow the guiding of the bearing as it moves upon and down to be doneentirely by means of the rods 52 and 53. This tends to reduce the friction of the parts and to allow greater freedom of motion of the journal bearing 32 in the vertical direction. lVhen, however, the journal bearing as a whole is removed from the journal 31 of the tension roll, the sides 60 4 and 61 by coaction with the interior faces of uprights 55 and 56, prevent the turning of the journal bearing 32 and hold it inposition. This facilitates the handling of the apparatus during assembly and disassembly.

The spring support 54 in the modified form of the apparatus is secured to the threaded post 45 in a somewhat different manner from the frame work 34 of Fig. 2. Spring support 54 has a laterally projecting lug 62 which is bolted to a corresponding lug 63 on a member 64 which encircles the threaded post 45 and which is held in place by the hand wheels 46 and 47. The outer ends of lugs 62 and 63 coact with I shoulders 65 and 66 on the opposite lugs 63 and 62 which, because of their relatively great vertical length, securely position the spring supports 54. With this arrangement, when it is desired to disassemble a tension roll, for example, for repairs, or for the replacement of the Fourdrinier wire; the tension roll bearing may be easily removed and' replaced in the exact position that it formerly occupied. It is only necessary to remove the two bolts which clamp together lugs 62 and 63, leaving member 64 in the position to which it has been adjusted on post 45. I

The rods or plungers 52 and 53 not only serve as guides for the journal bearing 32, but they also maintain the coils of springs '38 and 39 in proper alignment so as to pret'entthe buckling of the springs, that is,

the tendency for some of the coils to'move outwardly and interfere with the functionmg of the spring. Pointers 67 and 68 are mounted on the journal bearing 32. Pointer 67 moves over a scale at the left which indicates the force in pounds exerted by springs 38 or 39 and pointer 68 moves over a scale at the right which indicates the total ten sion or stretch existing in the wirecaused by the combined weight of tension roll 29 and the force exerted by the springs.

When a wire is operating in combination with a tension or stretch roll mounted as above described, the alternate stretching of the opposite edges of the wire which is caused bythe table roll=shake motion will be taken up by a lifting or lowering of one side or the other of the stretch roll 29.; this freedom of movement being possible because of the floating arrangement of the roll under the action of the w1re 10 and the springs 38 and 39. The initial tension applied to the wire depends primarily upon the weight of roll 29 and the relatively small arts directly connected thereto and thereore moving up and own with the roll, these parts being only the journals 31 and. bearings 32. For this, reason the inertia of these parts is relatively low and, even though the. shake motion is operated rapidly so that the tension in the wire is varying rapidly from side to side, nevertheless these changes are compensated-for in a practical manner so as to materially reduce the amount of stretch, or in other words the amount of permanent set in the wire.

Furthermore, by supporting the roll in a floating condition on the wire and providing the springs 38 and 39 which increasingly oppose any movement of the roll either upwardly or downwardly from this floating position, the stretch or tension roll is made-to be in a sense self-adjustable. By this it is meant that as the Fourdrinier wire expands under the action of heat or from any other cause, the change in tension is to a certain degree compensated and is accurately'indicated by the change of position' of the pointers on their respective scales. Thus the operator of the machine has a means of knowing accurately the exact tension under which the wire is operated. Any slackening of the wire caused by expansion will immediately show on the scale, thus allowing the operator to adjust the bearings accordingly and to avoid wrinkling of the wire when passing through the couch rolls and over the breast roll.

Should the stretch or tension roll not be of uniform density, that is, heavier atone end than the other, as is sometimes the case, especially in old machines, then, when starting a Fourdrinier wire, the indicating pointers on each side of the machine may be set so as to produce a uniform tension by a simple manipulation of the hand wheels 46 and 47 which varies the position of support of springs '38 and 39 and thus adds to or reduces the weight of the roll.

By controlling the wire in the manner described above, it is given a completely elastic working condition which eliminates severe strains and stresses, especially when accelerating the wire fromrest to full speed. Inasmuch as these wires are now operated at speeds as high as 1,000 feet per minute, it is easily understood that great care must be used in bringing the wire up to this speed inasmuch as it is an easy matter to accelerate too rapidly and permanently stretch the wire. The elasticity provided by; this improved control of the tension of Fourdrmier wires practically hazard.

I claim: 7 a

1. In a paper machine, an extensible and contractible belt, a roll supported thereon for applying tension thereto, journal bearings for the roll having vertical guides which allow the roll to float freely under the support of the belt, and means associated with said guides for increasingly opposing the movement of the roll above or below this floating position in proportion to the amount of this movement.

2. In a paper machine, an extensible and contractible belt, a roll supported thereon for applying tension thereto, journal bearings for the roll,--ha-vin vertical guides which allow the roll to float freely under the support of the belt, means associated with said guides for increasingly opposing the movement of the roll above or below this floating position in proportion to the amount of this movement, and means for indicating the relative position of'the bearings in their respective vertical guides.

eliminates this 3. In a paper machine, an extensible and contractible belt, a roll extending throughout the width of the belt and supported thereon for a plying tension thereto, a journal bearing or each end of the roll having vertical guides which allow the roll to float freely under the support of the belt, means associated with said guides for increasingly opposing the movement of the roll above or below this floating position in proportion to the extent of this movement, and means for independently adjusting the position of said opposing means with res ect to said bearings so as to equalize t e tension throughout the width of the belt.'

4. In a paper machine, an extensible and contractible belt, av roll supported thereon for applying tension thereto, journal bearings for the roll having vertical guides which allow the roll to float freely under the support of the belt, and a pair of springs, one above and one below each bearing and coacting therewith to increase or diminish the pressure applied to the belt by the wei ht of the roll as the roll moves in said gui es respectively above or below said oating position.

5. In a pa er machine, an extensible and contractible It, a roll supported thereon .forapplying tension ,thereto, journal bearings for the roll having vertical guides which allow the roll to float freely under the support of the belt, a. pair of springs, one above and one below each bearing and coacting therewith to increase or diminish the pressure applied to the belt b the weight. of the roll, and means for in icating the relative position of said bearings in said vertical guides.

6. In a paper machine, an. extensible and contractible belt, a roll supported thereon l for applying tension thereto, and journal controlling means for each end of the roll comprising, a journal bearing, guiding means therefor permitting the roll to float. freely under the support of the belt, a spring above and below the'journal bearing, said the belt by the weight of the roll, a vertically'adjustable support for said springs, and means associated with the journal bearing and said support for preventing the buck- '1ing of the springs when compressed.

8. In a paper machine, an extensible and contractible belt, a roll supported thereon for applying tension thereto, and journal controlling means for each end of the roll comprising, a journal bearing, guiding means therefor permitting the roll to floatfreely under the support of the belt, a coil spring above and below the journal bearing, said springs coacting therewith to increase or diminish the pressure appliedto the belt by. the wgight of the roll, a vertically adjustable support for said springs, and a rigid member extending longitudinally oi each spring for preventing the buckling of the springs when compressed.

9. In a paper machine, an'extensible and contractible belt, a roll supported thereon for applying tension thereto, and journal controlling means for each end of the roll comprising, a journal bearing havingrods rigidly secured at the top and bottom thereof respectively a vertically adjustable spring support aving apertures therein in which said rods slide, and a coil spring around each rod and coacting with the bearing and said support.

n testimony whereof I aflix my 81%1at1118.

FRANCIS W. WAR EN. 

